Our Trust's prophylactic antibiotic regime for elective hip and knee replacements recently changed, following the publication of Department of Health guidelines aimed at reducing the incidence of Clostridium Difficile associated diarrhoea (CDAD). We aimed to assess whether this change has reduced the incidence of post-operative CDAD. We reviewed all primary and revision total hip and knee replacements performed in Gloucestershire Royal Hospital between April 2007 and March 2010. Up to August 2008, patients received prophylaxis with cefuroxime (Group A). This subsequently changed to flucloxacillin and gentamicin (Group B). All patients who developed CDAD within one month of surgery were identified and their case-notes were reviewed for the presence of CDAD risk factors, such as concomitant use of broad-spectrum antibiotics. 3117 patients were included and 15 developed CDAD (0.48%); 12 patients (0.77%) from Group A and 3 from Group B (0.19%), representing a four-fold decrease. Analysis of a 2×2 contingency table with Fisher's exact test showed that the difference between the two groups was statistically significant (P=0.0347). Case-note analysis revealed that 8/12 patients in Group A and 1/3 patients in Group B had other risk factors for developing CDAD. Excluding these patients, the difference between the two groups was not statistically significant (P=0.218). CDAD is exceedingly rare following total joint replacement surgery, especially when the only antibiotics given are prophylactic. Our figures are in line with a general decline in CDAD nationally from 2007. This decline is most likely due to multiple factors, such as hand-washing, barrier nursing and restrictive antibiotic policies. The effect of the change in prophylaxis is therefore difficult to quantify. Choice of prophylactic antibiotics should be based upon their efficacy alone, not their potential to reduce CDAD.
It has been shown that a cognitive function (CF) loss can occur after hip or knee arthroplasty procedures, with an incidence of 40 to 70%. The pathogenesis remains unclear but studies suggest some form of brain emboli; although both trans-cranial doppler and trans-oesophageal doppler have both shown emboli per-operatively a correlation has never been shown with CF loss post-operatively. In contrast, in the cardiothoracic literature an embolic cause is widely accepted for detectable post-operative CF drop. The purpose of this study was to ascertain whether MRI could show evidence of embolic phenomena in patients undergoing hip or knee arthroplasty. Twenty-five patients presenting for hip or knee arthroplasty procedures were consented for this study. Brain MRI scans and MR angiograms were performed 1 week pre-operatively and within 1 week post-operatively using a Phillips 1.5Tesla MRI unit. All scans recorded were independently reviewed by 2 radiologists. A series of tests to examine several modes of cognitive function were carried out by a clinical psychologist pre-operatively, and at 1 week post-operatively. The CF tests showed a clinically significant drop following surgery in 64% of cases – this is in keeping with other recently published data. None of the post-operative scans or angiograms showed overt evidence of new lesions. Three Scans had equivocal tiny brainstem hypodensities on a single slice with no correlating abnormality on diffusion images to support the presence of new ischaemia. We conclude that either the aetiology of post-operative CF drop following arthroplasty is not embolic in nature, or that with current technology MRI brain scans even with angiograms are not sensitive enough to show the corresponding abnormality. With currently available equipment there appears to be no benefit from using MRI as a tool to evaluate post-operative CF loss in this group of patients.
